Usually though the saves are marked as Invalid right on the load game screen and it won't let you try. In the hop from beta 2 to 2.5 though they can still be loaded, just give a minidump at the start of the loading bar. I was actually curious last night so I tried too

Wouldn't blame folks for getting a little confused about it on this update because of it, though.

It couldn't have hurt to have said this before updating right?

I should have expected it but since the file size was so small I didn't. It does suck though I don't have that much time to play this game so every ruined save is another start from scratch which really is something that bugs me, well can't be changed now.
But maybe it's time that stardock introduced a roll back or unpatch function in impulse especially since there is no other way of patching your game. This would also help allot when a patch breaks the game and you have to wait for it to be fixed this way we can just use an older patch to make it work which could save allot of hassle. Obviously online mode wouldn't work but then again noone should expect it to work.